US9901331B2 - Spacer block - Google Patents

Abstract

A knee arthroplasty system for use in a patient's knee joint comprises a spacer block instrument including a base portion, a tibial component extending from the base portion and configured for placement against a tibia, and a femoral component configured for placement against a femur. The femoral component is rotatably coupled to the tibial component. The system further includes one or more spacer block shims structured for removable attachment to the tibial component.

Description

CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No. 14/034,076, filed on Sep. 23, 2013, the benefit of priority of which is claimed hereby, and which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to knee arthroplasty. More particularly, the present disclosure relates to an instrument for use during a knee arthroplasty procedure, and to a method for using the same.

BACKGROUND

In a total knee arthroplasty (TKA) procedure, a patient's distal femur is resected and replaced with a prosthetic femoral implant, and the patient's proximal tibia is resected and replaced with a prosthetic tibial implant. The prosthetic femoral implant articulates with the prosthetic tibial implant to restore joint motion.

Many factors influence joint motion after the TKA procedure. The size and shape of each prosthetic implant will impact joint motion. Additionally, the location and orientation of each prosthetic implant, which is determined by the location and orientation of the corresponding bone resections, will impact joint motion. The tension or laxity of the surrounding soft tissue will also impact joint motion. For example, if the surrounding collateral ligaments are too tense, joint motion may be limited, but if the surrounding collateral ligaments are too lax, improper femoral rotation or femoral lift-off may occur. Also, the soft tissue balance around the joint will impact joint motion.

Different surgical philosophies have traditionally influenced TKA instruments and procedures. For example, a first, “measured resection” philosophy emphasizes bone resections while preserving the natural joint axis and soft tissue. A second, “soft tissue balancing” philosophy emphasizes soft tissue modifications while preserving bone.

OVERVIEW

This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.

The present patent application provides an exemplary TKA instrument and procedure. The instrument can separate the patient's tibia and femur, in both extension and flexion, to place the knee joint in tension and to measure a gap and an angle therebetween. The instrument can include various modular accessories. The accessories can provide flexibility of usage throughout the TKA procedure. For example, the instrument can be used before resecting or otherwise manipulating the patient's knee joint to evaluate the natural knee joint and plan the TKA procedure, as well as after resecting or otherwise manipulating the patient's knee joint to evaluate and/or further plan the TKA procedure. The accessories can also allow each individual user to select accessories that accommodate his or her own surgical philosophy and the needs of the particular patient. The accessories can also allow the user to incorporate multiple surgical philosophies into a single surgical procedure, such as by comparing the potential outcome of one accessory with the potential outcome of another accessory.

According to an example of the present disclosure, a knee arthroplasty instrument can be provided for use in a patient's knee joint, which includes a tibia and a femur. The instrument can include a spacer tool and a spacer shim. The spacer tool can include a tibial component configured for placement against the tibia and a femoral component configured for placement against the femur. The tibial component can be structured to accept a shim to place the patient's knee joint in tension by separating the tibia and the femur. The shim can be removably coupled to the spacer tool to increase the effective height of the tibial component.

According to an example of the present disclosure, a knee arthroplasty method for a patient's knee joint can include: estimating a resection gap, selecting one of a set of spacer shims, attaching the selected spacer shim to a tibial component, inserting an instrument with the spacer shim attached into the resection gap to separate the tibia and femur to verify a joint gap and a joint angle prior to implantation of an artificial joint.

To further illustrate the knee arthroplasty system and method disclosed herein, a non-limiting list of examples is provided here:

In Example 1, a knee arthroplasty system for use in a patient's knee joint can be provided that includes a spacer block instrument including a base portion, a tibial component extending from the base portion and configured for placement against a tibia, and a femoral component configured for placement against a femur, wherein the femoral component is rotatably coupled to the tibial component. The system further includes one or more spacer block shims structured for removable attachment to the tibial component.

In Example 2, the system of Example 1 is optionally configured such that each of the one or more spacer block shims comprises a spacer component and a handle portion, wherein the handle portion is structured to be positioned adjacent to the base portion of the spacer block instrument.

In Example 3, the system of any one of or any combination of Examples 1-2 is optionally configured such that the one or more spacer block shims comprises a plurality of spacer block shims, each of the spacer block shims defining a different shim height.

In Example 4, the system of Example 3 is optionally configured such that the shim height of each of the plurality of spacer block shims is between about 10 mm and about 13 mm.

In Example 5, the system of any one of or any combination of Examples 1-4 is optionally configured such that each of the one or more spacer block shims includes a connector structured to removably engage, in the alternative, the tibial component of the spacer block instrument.

In Example 6, the system of Example 5 is optionally configured such that the connector is a sliding joint.

In Example 7, the system of Example 6 is optionally configured such that the sliding joint is a dovetail joint.

In Example 8, the system of any one of or any combination of Examples 5-7 is optionally configured such that the connector includes a ball detent mechanism.

In Example 9, the system of any one of or any combination of Examples 1-8 is optionally configured such that the base portion of the spacer block instrument includes one or more channels extending through the base portion and configured to receive one or more alignment rods.

In Example 10, the system of Example 9 is optionally configured such that the handle portion of the one or more spacer block shims includes one or more channels configured to at least partially align with the one or more channels in the base portion of the spacer block instrument.

In Example 11, the system of any one of or any combination of Examples 2-10 is optionally configured such that the handle portion of the one or more spacer block shims includes a fin portion extending in a direction generally perpendicular to an axis of the spacer block instrument.

In Example 12, the system of Example 11 is optionally configured such that the fin portion is curved.

In Example 13, the system of any one of or any combination of Examples 1-12 is optionally configured to include a scale plate extending from the base portion and a pointer extending from the femoral component.

In Example 14, the system of Example 13 is optionally configured such that the scale plate includes an arcuate slot configured to at least partially receive the pointer, wherein the pointer travels within the arcuate slot as the femoral component rotates relative to the tibial component.

In Example 15, the system of any one of or any combination of Examples 13-14 is optionally configured such that the scale plate includes a numerical scale defining a range of joint angles.

In Example 16, a method of using a knee arthroplasty instrument to evaluate a resected knee joint can be employed that includes observing a resection gap between a distally resected femur and a proximally resected tibia, selecting a first spacer block shim from a plurality of spacer block shims, attaching the first spacer block shim to a tibial component of the knee arthroplasty instrument, and inserting the knee arthroplasty instrument into the resection gap, including positioning the tibial component and attached first spacer block shim adjacent to the proximally resected tibia and positioning a femoral component of the knee arthroplasty instrument adjacent to the distally resected femur, the femoral component being rotatable relative to the tibial component. The method further includes evaluating tension in the resected knee joint, including determining a first joint angle formed between the tibial component and the femoral component.

In Example 17, the method of Example 16 is optionally configured to include removing the knee arthroplasty instrument from the resection gap, detaching the first spacer block shim from the tibial component, selecting a second spacer block shim from the plurality of spacer block shims, attaching the second spacer block shim to the tibial component, reinserting the knee arthroplasty instrument into the resection gap, and evaluating tension in the resected knee joint, including determining a second joint angle formed between the tibial component and the femoral component, and comparing the first joint angle to the second joint angle.

In Example 18, the method of any one of or any combination of Examples 16-17 is optionally configured such that each of the plurality of spacer block shims defines a different shim height.

In Example 19, the method of any one of or any combination of Examples 16-18 is optionally configured such that determining a first joint angle comprises observing a scale plate extending from the knee arthroplasty instrument.

In Example 20, the method of Example 19 is optionally configured such that the scale plate includes an arcuate slot configured to at least partially receive a pointer extending from the femoral component.

In Example 21, the system or method of any one of or any combination of Examples 1-20 is optionally configured such that all elements or options recited are available to use or select from.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals can be used to describe similar elements throughout the several views. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 is a perspective view of a knee arthroplasty instrument in accordance with an example of the present disclosure, the instrument including a base, a lower tibial component, an upper femoral component and a tibial spacer shim.

FIG. 2 is a top plan view of the instrument ofFIG. 1, in accordance with an example of the present disclosure.

FIG. 3 is a cross-sectional view of a portion of the instrument taken along line B-B ofFIG. 2, in accordance with an example of the present disclosure.

FIG. 4 is a distal end view of the instrument detailing alignment of key and keyway features, in accordance with an example of the present disclosure.

FIG. 5 is a distal end view of the instrument detailing an offset of the key and keyway features, in accordance with an example of the present disclosure.

FIG. 6 is an exploded perspective view of the instrument showing an example of a spring-loaded ball plunger attached to the lower tibial component, in accordance with an example of the present disclosure.

FIG. 7 is a bottom view of the upper femoral component showing an example of a detent channel, in accordance with an example of the present disclosure.

FIG. 8 is a perspective view of the tibial spacer shim ofFIG. 1, in accordance with an example of the present disclosure.

FIG. 9 is a perspective view illustrating the removable attachment of the tibial spacer shim to the instrument ofFIG. 1, in accordance with an example of the present disclosure.

FIG. 10 is an anterior elevational view of a knee joint in extension, in accordance with an example of the present disclosure.

FIG. 11 is an anterior elevational view of the knee joint in flexion, in accordance with an example of the present disclosure.

FIG. 12 is a perspective view of the instrument ofFIG. 1 with the tibial spacer shim positioned within the knee joint in extension, in accordance with an example of the present disclosure.

FIG. 13 is a perspective view of the instrument ofFIG. 1 with the tibial spacer shim positioned within the knee joint in flexion, in accordance with an example of the present disclosure.

DETAILED DESCRIPTION

With reference toFIGS. 1 and 2, aspacer instrument10 can be provided for separating a patient's tibia and femur and measuring a joint gap and a joint angle therebetween.Instrument10 can include abase portion12, ahandle portion13, alower tibial component14, an upperfemoral component16, apost30 configured to couplefemoral component16 totibial component14, and a tibialspacer block shim18.Base portion12 can include one ormore channels40 extending at least partially therethrough and oriented generally perpendicular to a plane formed bytibial component14 to allow for the use of one or more alignment rods in cooperation withinstrument10. As will be discussed in further detail below,femoral component16 andspacer block shim18 can be removably attached totibial component14 using a suitable connection means.Tibial component14,femoral component16 and spacer block shim18 (seeFIG. 1) can be offset frombase portion12, as shown inFIG. 2, to accommodate the patient's patella.

Femoral component16 can be configured to rotate relative totibial component14. More specifically,femoral component16 can be configured to rotate relative totibial component14 about rotation axis A. As shown inFIG. 2, post30 can engage withfemoral component16 at one or more locations along rotation axis A, andfemoral component16 can be configured to rotate aboutpost30. In an example, the rotation axis A offemoral component16 can be parallel to the longest dimension of thebase portion12, such as a longitudinal dimension extending between a proximal end and a distal end ofbase portion12.

An angle measuring means can be provided to measure an angle α betweentibial component14 andfemoral component16 about the rotation axis A. In an example, as illustrated inFIG. 1, the angle measuring means can include ascale plate32 extending frombase portion12. As further illustrated inFIG. 1,scale plate32 can define anarcuate slot34 configured to receive apointer36 extending fromfemoral component16. Asfemoral component16 rotates relative tobase portion12 about axis A,pointer36 can be configured to move along or througharcuate slot34 ofscale plate32. The angle α betweentibial component14 andfemoral component16 can be determined by reading the value fromscale plate32 that is adjacent topointer36. Whenfemoral component16 is oriented parallel totibial component14,pointer36 can be centered inslot34 corresponding to an angle α of 0 degrees. Asfemoral component16 deviates from this parallel orientation,pointer36 can move alongslot34 to a positive angle α greater than 0 degrees or a negative angle α less than 0 degrees. As discussed in further detail below, angle α can indicate a varus/valgus angle of the patient's knee joint and/or internal/external rotation of the patient's knee joint.

An angle rotation limiting means can be provided to restrict the angle of motion betweentibial component14 andfemoral component16 about rotation axis A. Referring toFIG. 1,femoral component16 can include afemoral cover90 with anouter surface92 and an inner surface94 (seeFIG. 3) that includes arotation restriction portion96 with one or more rotation restriction surfaces98. In an example,outer surface92 andinner surface94 can be located on circular arcs centered about axis A so that rotation offemoral component16 aboutpost30 can result in similar rotation offemoral cover90 about axisA. Tibial component14 can include one or more restriction pocket surfaces100 located onprojection102, which can be connected to post30 as shown inFIG. 6.Projection102 can extend frombase portion12 viawall104. In an example, asfemoral component16 rotates aboutpost30, the rotation angle α betweentibial component14 andfemoral component16 can be limited by the interference of arestriction surface98 with apocket surface100. As shown inFIG. 3, which is a cross-sectional view of a portion ofinstrument10 taken along line B-B ofFIG. 2, rotation angle α offemoral component16 can depend on the arc length L ofrotation restriction portion96.

Instrument10 can include a set of modular accessories, examples of which are described further below.Instrument10 and the accessories can be provided together as a system. In this manner, a surgeon or another user can select a first accessory from the system and attach that first accessory toinstrument10. As the surgical procedure progresses, the surgeon can select a second accessory from the system and attach the second accessory toinstrument10. In various examples, the first accessory can be left in place when the second accessory is attached toinstrument10. In other examples, the first accessory can be removed frominstrument10 to accommodate the second accessory. A variety of different coupling mechanisms (e.g., dovetail joints) and locking mechanisms (e.g., keys, ball detents) can be used to selectively receive and retain the desired modular accessory oninstrument10. Additional information regarding modular accessories forinstrument10 can be found in PCT Publication No. WO2013013094 to Claypool et al., entitled “Knee Arthroplasty Instrument,” the disclosure of which is incorporated herein by reference in its entirety.

FIG. 4 is a distal end view ofinstrument10 detailing attachment offemoral component16, which can be considered a modular accessory that can be removably coupled toinstrument10. In an example, a key50 can be located onpost30 and akeyway52 can be located infemoral component16 as shown inFIG. 4. Alignment ofkeyway52 with key50 can allow a surgeon to slidekeyway52 overkey50 along axis A in a direction towardhandle13 untilkey50 extends at least partially through femoral component16 (seeFIG. 2) thereby locatingfemoral component16 ontopost30 and allowingfemoral component16 to rotate freely aboutpost30.

FIG. 5 is a distal end view ofinstrument10 detailing an offset of the key50 andkeyway52 features. As shown inFIG. 5,keyway52 ordinarily remains offset from key50 during rotation offemoral component16 aboutpost30 so as to interfere with the motion offemoral component16 along axis A, thereby preventing detachment offemoral component16 frominstrument10 during use. Removal offemoral component16 can be effected by rotatingfemoral component16 aboutpost30 untilkeyway52 is once again aligned with key50 (seeFIG. 4), allowing a surgeon to slidefemoral component16 along axis A in a direction away fromhandle13 for removal overpost30.

FIG. 6 is an exploded perspective view ofinstrument10 illustratingfemoral component16 detached fromtibial component14.FIG. 7 is a bottom view offemoral component16 after removal frominstrument10. Together,FIGS. 6 and 7 depict exemplary features that can allowfemoral component16 to be removably coupled totibial component14.

In an example,instrument10 can include a ball detent mechanism to removably couplefemoral component16 totibial component14. A ball detent mechanism can include, but is not limited to, a spring-loaded ball plunger component in combination with a cavity located on an adjacent component. In an example,tibial component14 can include a spring-loadedball plunger82 as shown inFIG. 6 andfemoral component16 can include adetent channel80 located oninner surface94 offemoral cover90 as shown inFIG. 7. With reference toFIGS. 6 and 7,femoral component16 can be removably coupled totibial component14 by slidingfemoral component16 overpost30 along axis A towardhandle13 whereby the spring biasing force of spring-loadedball plunger82 engagesdetent channel80 so that motion offemoral component16 along axis A can be impeded.Femoral component16 can thereafter be removed fromtibial component14 by applying an axial force tofemoral component16 along axis A in a direction away fromhandle13 to overcome the spring biasing force applied by spring-loadedball plunger82 to channel80, thereby releasingfemoral component16 for sliding removal overpost30.

FIG. 8 is a perspective view ofspacer block shim18 removed frominstrument10. In an example,spacer block shim18 can also be considered a modular accessory that can be removably coupled toinstrument10 In use,spacer block shim18 can be removably coupled totibial component14 thereby increasing the overall effective thickness oftibial component14.Spacer block shim18 can be coupled totibial component14 to perform various functions, such as to adjust tension of soft tissue in the knee.Spacer block shim18 can include aspacer component64, aconnector66, and ashim handle portion68 with adistal end84 and aproximal end86. As illustrated inFIG. 8,spacer component64 can be configured to extend fromproximal end86. In an example,spacer component64 can be substantially of the same size and shape astibial component14. However, in various examples,spacer component64 can be provided in different shapes, sizes and thicknesses to vary the overall effective thickness oftibial component14. Thus, in an example, a plurality of spacer block shims18 havingspacer components64 with different thicknesses can be provided for selection by the surgeon or user.

Shim handleportion68 can be structured for placement adjacent to atibial side70 of base portion12 (seeFIG. 1). In an example,shim handle portion68 can be configured with the same general shape astibial side70 ofbase portion12. However,shim handle portion68 can assume any suitable shape. Shim handleportion68 can include one ormore channels72 that can align with the one ormore channels40 ofbase portion12 to allow for the use of one or more alignment rods in cooperation withinstrument10. As illustrated inFIG. 8,shim handle portion68 can include afin portion74 that can extend away from a plane formed byshim handle portion68 and away fromtibial side70 ofbase portion12. In an example,fin portion74 can be of a curved construction as shown inFIG. 8, and can extend generally perpendicular to the plane formed byshim handle portion68. However,fin portion74 can be provided in different shapes, sizes, thicknesses and locations alongshim handle portion68.

Spacer block shim18 can include any suitable means that allowspacer block shim18 to be removably coupled totibial component14 ofinstrument10, such as coupling means that allowspacer block shim18 to slide linearly relative totibial component14 during engagement. InFIG. 9, for example,spacer block shim18 can be removably coupled totibial component14 by a sliding engagement via one or more tongues60 ofconnector66 and one or morecorresponding grooves62 oftibial component14, where tongues60 onconnector66 are sized to slide into thecorresponding grooves62 intibial component14 along axis A. In another example, the sliding engagement ofspacer block shim18 andtibial component14 can alternatively or additionally utilize a ball detent mechanism betweenspacer block shim18 andtibial component14. The ball detent mechanism can include features similar to the spring-loadedball plunger82 and thedetent channel80 previously described.

An exemplary method of usinginstrument10 will now be described with reference toFIGS. 10-13. The order of the following steps can vary depending on factors such as the surgeon's preference, the patient's bone quality, the state of the patient's surrounding soft tissue, and the types of prosthetic implants being used.

First, the surgeon can perform pre-operative planning. The planning step can involve taking X-rays or other images of the patient's knee joint200 and selecting prosthetic implants to accommodate the patient's needs, for example.

Next, as shown inFIGS. 10 and 11, the surgeon can exposetibia202 andfemur204 of the patient's knee joint200. The exposing step can involve incising the patient's skin, incising the patient's joint capsule, and removing osteophytes, for example.

With the patient's knee joint200 now exposed, the surgeon can useinstrument10 toseparate tibia202 andfemur204 of the patient's knee joint200 to a predetermined tension, and to plan and identify the desired bone resections oftibia202 andfemur204. With the patient's knee joint200 tensioned in extension (FIG. 10), the surgeon can plan and identify aproximal tibial resection206 and a distalfemoral resection208 that will produce a desired gap G and angle α therebetween. The extension angle α can be referred to as a varus/valgus angle. With the patient's knee joint200 tensioned in flexion (FIG. 11), the surgeon is able to plan and identify theproximal tibial resection206 and a posteriorfemoral resection210 that will produce a desired gap G and angle α therebetween. The flexion angle α can be referred to as an internal/external rotation angle. Gap G and angle α betweentibia202 andfemur204 can be selected based on the patient's age, the patient's bone quality, the state of the patient's surrounding soft tissue, the types of prosthetic implants being used, and other factors, for example.

Tibia202 andfemur204 can be resected using suitable cut guides. For example, the Minimally Invasive Surgery (MIS) Tibial Cut Guide Assembly, which is available from Zimmer, Inc. of Warsaw, Ind., can be used to form theproximal tibial resection206 intibia202. Suitable cut guides can also be used to form the distalfemoral resection208 and the posteriorfemoral resection210 infemur204.

In addition to evaluating bone resections, the surgeon can also evaluate soft tissue resections, releases, or other soft tissue operations that would impact gap G and angle α betweentibia202 andfemur204. For example, if the surgeon desires a balanced angle α of 0 degrees betweentibia202 andfemur204, the surgeon can release or otherwise relax ligaments on one side of the patient's knee joint200 (e.g., the medial side) relative to the opposing side of the patient's knee joint200 (e.g., the lateral side). As another example, if the surgeon desires a larger gap G betweentibia202 andfemur204 without resecting additional bone fromtibia202 orfemur204, the surgeon can release or otherwise relax ligaments around the patient's knee joint200.

According to an example of the present disclosure, knee joint200 can be prepared such that gap G and angle α betweentibia202 andfemur204 are the same or substantially the same in extension (FIG. 10) as in flexion (FIG. 11). In this example, a three-dimensional space can be maintained betweentibia202 andfemur204 in extension and flexion. For example, a surgeon implanting a prosthetic femoral implant having equally thick distal and femoral condyles can prepare an extension gap G that is the same as the flexion gap G, while a surgeon implanting a prosthetic femoral implant having distal and femoral condyles of different thicknesses can prepare an extension gap G that varies the flexion gap G to account for the different thicknesses. When angle α is 0 degrees, such that theproximal tibial resection206 is parallel to the distalfemoral resection208 in extension (FIG. 10) and the posteriorfemoral resection210 in flexion (FIG. 11), the three-dimensional space betweentibia202 andfemur204 will be substantially rectangular in shape in extension and flexion. It is also within the scope of the present disclosure that the surgeon may tolerate differences between the extension angle α (FIG. 10) and the flexion angle α (FIG. 11), such as differences of 1 degree, 2 degrees, 3 degrees or more.

In view of the foregoing,instrument10 can be used to measure the natural gap G and angle α betweentibia202 andfemur204 in extension and flexion, and to plan or identify theproximal tibial resection206, the distalfemoral resection208, the posteriorfemoral resection210, and/or any soft tissue resections that will produce a desired gap G and angle α betweentibia202 andfemur204 in extension and flexion. Additionally, after resecting or otherwise manipulating knee joint200,instrument10 can be used to verify the desired gap G and angle α betweentibia202 andfemur204 in extension and flexion. Therefore,instrument10 can be used before and/or after resecting or otherwise manipulatingknee joint200.

The use ofinstrument10 to measure gap G and angle α betweentibia202 andfemur204 is described further with reference toFIGS. 12 and 13, for example. InFIG. 12,instrument10 is illustrated as being used with the patient's knee joint200 in extension.Proximal tibial resection206 has already been formed intibia202, and distalfemoral resection208 has already been formed infemur204. Thus, in the illustrated example ofFIG. 12,instrument10 is being used to verify the resected gap G and the resected angle a betweentibia202 andfemur204. A firstspacer block shim18 can be removably coupled totibial component14 ofinstrument10 so that firstspacer block shim18 contacts the resected tibial surface when theinstrument10 is inserted into the resection gap G. The firstspacer block shim18 can be preselected with knowledge of the resected gap G to verify the desired resected gap G and resected angle α have been achieved.

After attaching firstspacer block shim18 toinstrument10, firstspacer block shim18 can be placed againstproximal tibial resection206.Femoral component16 can be coupled throughpost30 totibial component14 and placed against distalfemoral resection208.FIG. 12 shows an embodiment offemoral component16 that can includespacing portion212,indicator portion214 andpad portion216.Indicator portion214 can terminate inpointer36.Pad portion216 can be thicker thanindicator portion214 andspacing portion212.FIG. 13 shows an embodiment offemoral component16 wherespacing portion212 does not includepad portion216. Withtibial component14 andfemoral component16 ofinstrument10 positioned toseparate tibia202 andfemur204, the surgeon can check the extension gap G between proximaltibial resection206 and distalfemoral resection208. Also, the surgeon can measure the extension angle between proximaltibial resection206 and distalfemoral resection208 by referencingscale plate32 onbase portion12 andpointer36 onfemoral component16.

Where the resulting tension in the knee is deemed to be insufficient,instrument10 can be removed from the resection gap G, firstspacer block shim18 can be removed frominstrument10 and a second spacer block shim that is incrementally larger than firstspacer block shim18 can be removably attached toinstrument10. Thereafter,instrument10 can be reinserted into the resection gap G as described previously. Where the resulting tension in the knee is deemed to be excessive,instrument10 can be removed from the resection gap G, firstspacer block shim18 can be removed frominstrument10 and a second spacer block shim that is incrementally smaller than firstspacer block shim18 can be removably attached toinstrument10 and thereafter reinserted in the resection gap G as previously described.

InFIG. 13,instrument10 is illustrated as being used with the patient's knee joint200 in flexion.Proximal tibial resection206 has already been formed intibia202, and posteriorfemoral resection210 has already been formed infemur204. Thus, as shown inFIG. 13,instrument10 is being used to verify the resected gap G and the resected angle α betweentibia202 andfemur204. A firstspacer block shim18 ofinstrument10 can be placed againstproximal tibial resection206.Femoral component16 can be coupled throughpost30 totibial component14 ofinstrument10 and placed against posteriorfemoral resection210. With firstspacer block shim18 andfemoral component16 ofinstrument10 positioned toseparate tibia202 andfemur204, the surgeon can verify that the flexion gap G ofFIG. 13 is the same as or substantially the same as the extension gap G ofFIG. 12. Also, the surgeon can verify that the flexion angle α ofFIG. 13 is the same as or substantially the same as the extension angle α ofFIG. 12. AlthoughFIGS. 12 and 13 only show distalfemoral resection208 and posteriorfemoral resection210 infemur204, other resections (e.g., chamfer cuts and an anterior cut) may also exist infemur204 wheninstrument10 is in use.

Where the resulting tension in the knee is deemed to be insufficient,instrument10 can be removed from the resection gap G, firstspacer block shim18 can be removed frominstrument10 and a second spacer block shim that is incrementally larger than firstspacer block shim18 can be removably attached toinstrument10. Thereafter,instrument10 can be reinserted into the resection gap G as described previously. Where the resulting tension in the knee is deemed to be excessive,instrument10 can be removed from the resection gap G, firstspacer block shim18 can be removed frominstrument10 and a second spacer block shim that is incrementally smaller than firstspacer block shim18 can be removably attached toinstrument10 and thereafter reinserted in the resection gap G as previously described.

If necessary, the patient's knee joint200 can be manipulated to adjust the measured gap G and/or the measured angle α betweentibia202 andfemur204. For example, if the surgeon determines that the flexion gap G ofFIG. 13 is too small compared to the extension gap G ofFIG. 12, the surgeon can cut a deeper posteriorfemoral resection210 to increase the flexion gap G ofFIG. 13. The surgeon can also make any necessary ligament adjustments to balance the soft tissue aroundknee joint200. For example, the surgeon can release the patient's posterior cruciate ligament (PCL), which has been shown to increase the flexion gap G relative to the extension gap G.

FIGS. 12 and 13 depict post-resection use ofinstrument10, withinstrument10 being positioned against resected bone surfaces oftibia202 andfemur204. As discussed above,instrument10 can also be used pre-resection, withinstrument10 being positioned against natural, un-resected bone surfaces oftibia202 andfemur204. In this pre-resection condition,instrument10 can communicate the pre-resection gap G and the pre-resection angle α between the natural, un-resected bone surfaces in extension and flexion. The surgeon can predict the post-resection values by combining the pre-resection values with the planned resections. For example, the surgeon can estimate the post-resection gap G by adding the planned resection depths to the corresponding pre-resection gap G.

The above Detailed Description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls. In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.”

In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims (23)

What is claimed is:

1. A knee arthroplasty system for use in a patient's knee joint, the knee joint including a tibia and a femur, the system comprising:

a spacer block instrument including a base portion, a tibial component connected to the base portion and configured for placement against a tibia, and a femoral component connected to the base portion and configured for placement against a femur, the femoral component being rotatable relative to the tibial component; and

one or more spacer block shims structured for removable attachment to the spacer block instrument to increase an overall thickness of the spacer block instrument across the tibial component and the femoral component.

2. The system ofclaim 1, wherein each of the one or more spacer block shims comprises a spacer component and a handle portion, wherein the handle portion is structured to be positioned adjacent to the base portion of the spacer block instrument.

3. The system ofclaim 2, wherein the one or more spacer block shims comprises a plurality of spacer block shims, each of the spacer block shims defining a different shim height.

4. The system ofclaim 2, wherein each of the one or more spacer block shims includes a connector structured to removably engage, in the alternative, the spacer block instrument.

5. The system ofclaim 4, wherein the connector is a sliding joint.

6. The system ofclaim 5, wherein the connector includes a ball detent mechanism.

7. The system ofclaim 2, wherein:

the base portion of the spacer block instrument includes one or more channels extending through the base portion and configured to receive one or more alignment rods; and

wherein the handle portion of the one or more spacer block shims includes one or more channels configured to at least partially align with the one or more channels in the base portion of the spacer block instrument.

8. The system ofclaim 2, wherein the handle portion of the one or more spacer block shims includes a fin portion extending in a direction generally perpendicular to an axis of the spacer block instrument.

9. The system ofclaim 1, wherein the spacer block instrument further comprises a scale plate extending from the base portion and a pointer extending from the femoral component, the scale plate including an arcuate slot configured to at least partially receive the pointer, wherein the pointer travels within the arcuate slot as the femoral component rotates relative to the tibial component.

10. The system ofclaim 1, wherein each of the one or more spacer block shims comprises a spacer component configured to engage the tibial component.

11. The system ofclaim 1, wherein:

the tibial component extends directly from the base portion; and

the femoral component is indirectly connectable to the base portion via rotatable coupling to the tibial component.

12. The system ofclaim 1, wherein the femoral component and the tibial component are configured for rotatable coupling at a post along a rotation axis extending through the tibial component and the femoral component.

13. The system ofclaim 12, wherein the tibial component includes a projection at which the post is located.

14. A spacer block instrument for a knee arthroplasty procedure, the spacer block instrument comprising:

a base portion;

a tibial component configured to connect to the base portion, the tibial component comprising an outside tibia-facing surface;

a femoral component configured to connect to the base portion, the femoral component comprising an outside femur-facing surface;

a handle portion extending from the base portion; and

a connection structure disposed on the spacer block instrument for receiving a spacer block shim;

wherein the femoral component is rotatable relative to the tibial component.

15. The spacer block instrument ofclaim 14, further comprising a spacer block shim having a spacer thickness, wherein the spacer block instrument has an instrument thickness comprising a distance between the outside tibia-facing surface and the outside femur-facing surface, wherein the spacer block shim is couplable to the connection structure to increase an overall thickness of the spacer block instrument.

16. The spacer block instrument ofclaim 15, wherein the spacer block shim is couplable to the outside tibia-facing surface of the tibial component.

17. The spacer block instrument ofclaim 14, wherein the tibial component extends directly from the base portion in order to connect to the base portion.

18. The spacer block instrument ofclaim 14, wherein the femoral component is configured for rotatable coupling to the tibial component in order to connect to the base portion.

19. The spacer block instrument ofclaim 14, wherein the femoral component and the tibial component are configured for rotatable coupling at a post extending along a rotation axis.

20. The spacer block instrument ofclaim 14, wherein the femoral component further comprises a pad portion that increases a thickness of the femoral component relative to thicknesses of other portions of the femoral component.

21. A method of using a knee arthroplasty instrument, the method comprising:

selecting a first spacer block shim from a plurality of spacer block shims;

attaching the first spacer block shim to the knee arthroplasty instrument;

rotating a femoral component of the knee arthroplasty instrument relative to a tibial component of the knee arthroplasty instrument; and

observing an angular position between the femoral component and the tibial component.

22. The method ofclaim 21, wherein rotating a femoral component of the knee arthroplasty instrument relative to a tibial component of the knee arthroplasty instrument comprises rotating the femoral component against the tibial component.

23. The method ofclaim 21, wherein attaching the first spacer block shim to the knee arthroplasty instrument comprises attaching the first spacer block shim to the tibial component to increase an overall thickness of the knee arthroplasty instrument across the tibial component and the femoral component.

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